Method and apparatus for producing radiation

ABSTRACT

The disclosure is of a method and apparatus for producing high energy radiation. A conducting liquid stream flowing between two electrodes is subjected to a large current pulse to cause the liquid stream to explode and produce radiation.

Related U.S. Application Data Continuation-impart of Ser. No. 608,245, Dec. 5, 1966, abandoned, which is a continuation-in-part of Ser. No. 263,830, March 8, 1963, abandoned.

UNITED STATES PATENTS 12/1964 Buchman 331/945 X Umted States Patent 1191 1111 3,777,208 Ryason Dec. 4, 1973 [54] METHOD AND APPARATUS FOR 655,176 8 1900 Ackermann 313 231 x PRODUCING RADIATION 2,436,090 2/ 1948 BOdine 3.15/11! X 2,899,864 8/1959 BIOXSOm 313 231.5 Inventofl Porter y San Anselmo, 3,182,496 5 1965 Holderer. 313 231.5 Calif. 3,201,635 8 1965 Carter..... 313 231 x 3,233,147 2 1966 Ducati 315 111 [73] Assgneei P Reseafch San 3,289,026 11 1966 Elton 313/231 Franclsco, callf- 3,290,552 12/1966 Van ()mum 315/111 [22] Filed, July 5 1968 2,567,037 9 1951 Smits 313 231 x 9 [21] Appl' 747044 Primary ExaminerJohn W. Huckert Assistant Examiner-Andrew J. James Attorney--J. A. Buchanan, Jr., R. L. Freeland, Jr., E. J. Keeling, G. F. Magdeburger and Burns, Doane, Swecker & Mathis 5 7 ABSTRACT The disclosure is of a method and apparatus for producing high energy radiation. A conducting liquid stream flowing between two electrodes is subjected to a large current pulse to cause the liquid stream to explode and produce radiation.

19 Claims, 4 Drawing Figures PATENTEUUEC 4mm 3,777. 208

SPARK GAP (VARIABLE) HIGH VOLT.

SUPPLY (VARIABLE)/ CAPACITOR JET FIG.'1

| u l l l l I l I V,

IINVENTOR PORTER R. RVASON BY f! M M METHOD AND APPARATUS FOR PRODUCING RADIATION This application is a continuation-in-part application of Ser. No. 608,245, filed Dec. 5, l966 and now abandoned which in turn is a continuation-in-part of Ser. No. 263,830, filed Mar. 8, 1963 and now abandoned.

This invention relates to methods and apparatus for providing high energy pulses and, more particularly, this invention relates to methods and apparatus for exploding a conducting liquid stream to produce a repetitive flash of high ultraviolet output.

In a broad aspect the present invention includes a methodand apparatus for providing repetitive high energy pulses. The invention provides for establishing a fine stream or jet of a flowable conducting material between two electrodes and then applying a large potential to the electrodes to cause an explosion of the stream to produce high intensity radiation with the spectrum lying largely in the ultraviolet region.

There are many instances when repetitive high intensity light flashes are needed. For example, in flash photolysis it is often desirable to provide repetitive light flashes of high ultraviolet output. It is also sometimes desirable to repetitively excite a laser at a high repetition rate; for example 1,000 times a second. Other uses for repetitive high energy pulses will also be apparent to those skilled in the art.

Heretofore energy in the ultraviolet region of the spectrum has been supplied by exploding a wire or by other means. This was accomplished by subjecting a thin wire to a large current pulse. A problem arose, however, in prior art methods when it was desired to produce a repetitive flash because the wire had to be renewed to produce each flash. This was a timeconsuming operation and could not be reproduced on a rapid basis.

It is a principal object of this invention to provide a method and apparatus for supplying repetitive high energy pulses having a substantial portion of energy in the ultraviolet region of the spectrum.

Further objects and advantages of the present invention will become apparent from reading the following detailed description in view of the accompanying drawing which is a part of this specification and in which:

FIG. 1 is a circuit diagram for-use in the present invention.

FIG. 2 is an alternative circuit diagram for use in the present invention.

FIG. 3 is a plan view and illustrates a preferred embodiment of apparatus of the present invention.

FIG. 4 is a sectional view taken at line 33 of FIG. 3.

With reference to the drawings and to FIG. 1 in particular, the present invention will be described in detail. In the present invention a conducting liquid stream or jet flowing between two electrodes is subjected to a large current pulse. The amount of energy required to explode a given stream is a function of the amount of energy stored and the rate at which it can be delivered. It is in accordance with the present invention to provide an energy storage means to store an adequate level of energy which energy can be pulsed to the conducting jet at a rate sufficient to explode the jet.

Suitable circuitry for an energy storage means is shown in FIG. 1. The capacitor circuit there shown will provide a sufficient energy pulse to explode a liquid stream. The current pulse is provided by connecting the stream of conducting liquid by appropriate means I in series with a voltage supply and a capacitor. The capacitor is charged to a high level and is allowed to discharge. The energy of the capacitor is dissipated in the stream of the liquid conductor causing the conductor to explode. The size of the'capacitor and the rate of discharge may be adjusted to appropriate levels to cause explosion of a given size stream of conducting liquid.

In order to cause the stream of conducting liquid to explode, it is necessary to subject the liquid jet or stream to a very large amount of energy in a relatively short period of time. The energy is supplied to the liquid stream by discharging an energy storage means through the stream. The characteristics of the light caused by exploding the conducting stream are determined to a large extent by the capacitor characteristics. It is highly desirable to use a capacitor having a small discharge time. For example capacitors with discharge times on the order of 0.2 milliseconds or less have been used in practicing the invention.

The output of the capacitor is also important to the present invention. The capacity must be sufficient to cause the jet of conducting material to explode. In the presence of air the explosion of the jet is characterized by a loud report. This feature of the present invention can be effectively utilized where repetitive explosions are required. It is immediately evident when sufficient energy has been pulsed through the jet to cause it to explode. Depending on the material used and the size of the jet, capacitors of at least one microfarad and capable of producing a potential of at least 1 kilovolt are preferred for use in the invention. It is preferred to use a capacitor of sufficiently high storage capacity to be sure to explode the jet. Thus capacitors on the order of microfarads to 160 microfarads have been used in practicing the invention. The high voltage supply is used to charge the capacitor.

With reference to FIG. 2 alternative circuitry for providing an energy pulse to explode the jet of conducting material is shown. The circuit there illustrated is an inductive storage circuit. Generally the discharge time for inductive circuits are longer than the discharge times for capacitor circuits, however a suitable energy level to explode a jet can be obtained with the circuit illustrated in FIG. .2.

A conducting liquid forms a fine stream between two electrodes. A wide variety of conducting liquids can be used in the present invention. The resistivity of the conducting liquid must fall within definite limits. The term conducting liquid of course is meant to include both substances which are liquid at ambient temperatures and substances which can be liquefied at temperatures in excess of ambient but still within operational temperature limits of the apparatus being utilized. The absolute upper resistivity limit for the conducting liquid to obtain desirable explosions in accordance with the present invention is 25 ohms-cm. The highly preferred upper limit, however, is on the order of 10 ohms-cm. The lower limit is in the range of about 5 microohmscm, although liquids having higher conductivity can be used. Thus the highly preferred range for the resistivity of the conducting liquids is between microohms-cm to 10 ohms-cm. A number of liquid substances have resistivities within this range and they are substances which are useful in the present invention.

Metals which are liquids below C. and preferably below 25 C. are preferred. The preferred conducting metal is mercury. Other metals, liquid at below 25 C., include eutectics of mercury, potassium, sodium, and rubidium with caesium; indium, silver, tin, and zinc with gallium; indium, sodium, rubidium, and thallium with mercury; potassium with sodium and rubidium with sodium. Metals liquid below 100 C. include caesium, gallium, potassium, sodium, rubidium, the binary eutectics: gold-sodium, bismuth-indium, cadmiumsodium, mercury-potassium, potassium-rubidium, and various multicomponent eutectics of mercury, gallium, caesium, potassium, sodium, rubidium, indium, tin, zinc, thallium, bismuth, cadmium, and lead. Some metals which melt at about 100 C. such as lithium, for example, may be utilized in the present invention when it is desired to produce a particular type of reaction.

Conducting solutions of electrolytes can also be used in the present invention. Among the salts included to make aqueous solutions used in the present invention are sodium chloride, calcium chloride, sodium sulfate, potassium iodide, nickelous acetate, tetramethyl ammonium bromide, and silver nitrate.

The conducting liquids listed above all have resistivities in the range of from 5 microohms-cm to 10 ohmscm. For example, the preferred conducting liquid, mercury, has a resistivity of 94 microohms-cm at C. Liquid sodium has a resistivity of 10 microohms-cm at 1 16 C. Liquid caesium has a resistivity of 37 microohms-cm at 30 C. Liquid lithium has a resistivity of 45 microohms-cm at 230 C. The conducting liquid metals mentioned above generally have much lowerresistivities than the conducting liquid solutions. For example, a potassium iodide solution containing 30 grams salt per 100 grams solution has a resistivity of 4 ohmscm. The same concentration of sodium chloride solution also has a resistivity of 4 ohms-cm. A 30 gram salt per 100 grams solution of silver nitrate has a resistivity of about 8 ohms-cm. Thus all of the above-mentioned conducting liquids including both liquid metals and salt solutions have resistivities within the highly preferred range of from about microohms-cm to 10 ohms-cm.

Liquids having resistivities in excess of 10 ohms-cm but less than 25 ohms-cm can, under some conditions, also be utilized as the conducting liquid in accordance with the present invention. While there are certain technical equipment difficulties in using these liquids with lower conductivities, it may sometimes be desirable to do so. Sea water, for example, has a resistivity of 21 ohms-cm and can be used in accordance with the method of the present invention in its natural state, although higher voltage requirements and apparatus to]- erances are required. In the case of sea water, it is preferred to add salt to the sea water to bring it within the highly preferred range of below 10 ohms-cm. A solution of lithium chloride and methanol which has a resistivity of between about 20-25 ohms-cm can also, under certain conditions, be utilized in accordance with the present invention.

Generally when using a conducting electrolyte solution it has been discovered that if the air gap of the capacitor is too small, it will break down prematurely and the liquid stream will glow rather than explode. The glow is of the characteristic color of the cation of the electrolyte. The phenomenon was observed with an air gap set to break down at about 2.8 kilovolts. To overcome this tendency the voltage was increased to a higher level to cause explosive breakdown of the stream. When the air gap was set to break down at 4 kilovolts, the stream exploded without a glowing phase. The exploding aqueous silver nitrate jet left behind relatively large quantities of finely divided silver metal. Thus a relatively high temperature on the order of 10,000 K. was attained during the explosion of the jet. The invention is therefore useful as a high temperature short reaction time chemical reactor. This is particularly true where a repetitive process requiring high temperature is required.

The stream of flowable conducting material as listed above is caused to explode by the discharge of the energy storage means. Immediately after exploding the stream reforms itself and another explosion can take place. In this manner repetitive flashes can be produced at an extremely rapid rate.

Referring now to FIG. 3 and FIG. 4, a preferred embodiment of apparatus assembled in accordance with the present invention is shown. A reservoir means 20 is provided for holding a quantity of the flowable conducting material. The reservoir means 20 is preferably constructed of a nonconducting material. Since it is necessary to provide a fine stream or jet of the flowable material for explosion, it must be contained in the reservoir under pressure. One suitable means for pressurizing the reservoir and the conducting material contained therein includes a tube connected to the upper portion of the reservoir in a fluid-tight manner by an appropriate connection such as cap 24. The other end of the tube 22 (not shown) is connected to a high pressure source of fluid, for example nitrogen. A suitable amount of pressure is maintained on the flowable material in the reservoir by adjusting the pressure of the fluid in the space 28 above the flowable material 26 contained in reservoir 20.

The lower end of reservoir 20 is provided with an orifice 30 as the only outlet for the conducting liquid from the reservoir. The orifice 30, may for example be found in a bulkhead 32 which closes off the lower end of the reservoir. An appropriate O-ring 34 is provided to seal the connection between the bulkhead 32 and the reservoir 20. It is preferred to use an orifice having a diameter at its outlet of less than about 0.01 inch so that a suitable jet is formed. Orifices as small as 0.001 inch are usable in the present invention. It is preferred to use an orifice having a diameter of between about 0.01 and 0.005 inch. The bulkhead 34 which forms the orifice 30 is constructed of a conducting metal and acts as an electrode.

The jet of the liquid conducting material must be a physically continuous stream of liquid. The cross section of the jet must be relatively small compared to the other components in the circuit so that the power will be dissipated in the jet and not elsewhere in the circuit. It is critical that the jet be an uninterrupted continuous stream of liquid; that is, the jet should be continuous rather than drop-like in form. in order to determine whether a jet has the proper configuration in accordance with the present invention, the jet is first established and the resistance of the jet is measured. This measured resistance should be substantially equal to the resistance of a column of the same conducting liquid under similar conditions having the same dimensions as the jet. The resistance of the conducting liquid may be calculated by the well-known fonnula set out below:

where R resistance in ohms p resistance in ohms-cm l length of column in cm A cross section of column in cm The orifice 30 directs a stream or jet indicated by the numeral 21 of the conducting liquid or solution to a small well 36 formed in a plug 38 of electrically conducting material. The well forms a second electrode and it is connected to ground by a suitable connection such as cable 40. The well 36 may be sized to contain surplus conducting liquid or solution. Thus the portion of the liquid which is not vaporized during the explosion may be stored in the well. If greater capacity is desired a conduit may be taped in plug 38 to allow the liquid to continuously drain off. The distance between the well 36 and the orifice 30 is adjustable. For example, the distance may be varied by moving plug 38 in or out of the threads 42 provided in a base member 44.

The maximum spacing between the electrodes 30 and 36 depends on the configuration of the stream of conducting liquid which can be established between them. As noted above, it is critical to have a physically continuous stream of conducting liquid of a relatively small cross section flowing between the two electrodes. Thus the maximum distance that the electrodes may be spaced apart is determined primarily by the problem of establishing a suitable jet for exploding between them. Spacing of from 4 to 6 inches between the electrodes is readily achievable in accordance with the preferred embodiment of apparatus of the present invention. The minimum spacing between electrodes is limited by the gas surrounding the electrodes. This is because if the electrodes are too close together the high potential will break down the gas rather than the conducting liquid jet and the benefit of the present invention will be lost. The minimum distance that the electrodes can be spaced apart can be varied by changing the gas around the electrodes and by increasing the pressure on the gas to prevent unwanted breakdown or ionization of the gas prior to exploding the liquid stream. For example, narrower spacing between the electrodes can be achieved with nitrogen or oxygen than with argon. The electrodes may be even more closely spaced when, for example, sulfur hexafluoride at relatively high pressure is the gas surrounding the electrodes.

The space between the orifice 30 and the well 36 is preferably enclosed by a nonconducting material to prevent splattering of the conductive liquid as it explodes. The liquid stream may however be exploded to the atmosphere. The liquid stream also can be exploded in a vacuum or under pressure. Oxygen need not be present and the explosion may take place in an inert environment. When a conducting metal is used the explosion may take place underwater. Thus the following description of a discharge box is by way of example only and is not intended by way of limitation. Thus a suitable discharge box is formed by base member 44; side walls 46, 48, 50 and 52; and roof member 54. A nonconducting member 56 is provided to receive a conducting member 58 which is in electrical communication with orifice 30. One of the side walls such as side wall 50 is preferably slidably removable so that easy access is obtainable to the interior of the discharge box 39.

The orifice 30 is connected into the circuitry of the present invention in a suitable manner. For example, conducting member 58 is provided with a threaded well to receive a bolt 60 and cable 62. Thus the orifice 30 and the well 36 form a pair of spaced-apart electrodes. The conducting liquid is sprayed in a fine stream of jet between the two electrodes. An energy pulse is passed through the stream to explode it. The streamis re- .formed almost immediately after the pulse and it is again ready to be exploded.

Although only a few specific embodiments of appara-.

tus have been disclosed, the invention is not limited to those specific embodiments but is meant to include all equivalents coming within the scope of the appended claims.

I claim:

. 1. Apparatus for repetitively producing high energy pulses comprising a pair of spaced-apart electrodes, reservoir means for holding a liquid-conducting substance, a liquid conducting substance having a resistivity of less than 25 ohms-cm in said reservoir, orifice means in electrical contact with one of said pair of spaced-apart electrodes and communicating with said reservoir for jetting a physically continuous stream of said liquid conducting substance to the other of said pair of electrodes and energy storage means operably connected to said electrodes, said energy-storing means having a capacity sufficient to cause said stream to explode.

2. The apparatus of claim 1 where the liquidconducting substance has a resistivity of between 5 microohms-cm and 10 ohms-cm.

3. The apparatus of claim 1- further characterized by discharge box means formed about said electrodes, saiddischarge box means being formed of a nonconductive material. I

4. Apparatus for repetitively producing high energy pulses comprising a pair of spaced-apart electrodes, the said electrodes being spaced apart at least a predetermined minimuni distance depending on the gaseous environment of the electrodes to prevent breakdown of the gas when a predetermined potential is applied across said electrodes, reservoir means for holding a conducting liquid, a conducting liquid in said reservoir means, said conducting liquid having a resistivity of less than 25 ohms-cm, orifice means in electrical contact with one of said pair of spaced-apart electrodes and communicating with said reservoir for jetting a physically continuous stream of said conducting liquid to the other pair of said electrodes, said stream conducting liquid having a relatively small cross section and having substantially the same resistance as a column of similar conducting liquid of the same length and cross section and energy storage means operably connected to said electrodes, said energy storage means having a capacity sufficient to cause said stream to explode.

5. Apparatus as in claim 4 where the conducting liquid is selected from the group consisting of mercury, potassium, sodium, rubidium with caesium, indium, silver, tin, zinc with gallium, indium with mercury, sodium with mercury, rubidium with mercury, thallium with mercury, potassium with sodium, rubidium with sodium, caesium, gallium, gold with sodium, bismuth with indium, cadmium with sodium, mercury with potassium, potassium with rubidium, lithium, sodium chloride solution, calcium chloride solution, sodium sulfate solution, potassium iodide solution, nickelous acetate solution, tetramethyl ammonium bromide solution and silver nitrate solution.

6. Apparatus of claim 4 where the conducting liquid has a resistivity of between microohms-cm and ohms-cm.

7. Apparatus of claim 4 characterized in that the energy storage means includes a capacitor.

8. Apparatus of claim 4 characterized in that the energy storage means includes a coil.

' 9. Apparatus of claim 4 characterized in that the energy storage means is capable of supplying a potential of at least 1 kilovolt.

10. Apparatus of claim 4 characterized in that the energy storage means is capable of supplying a potential of at least 1 kilovolt and has a discharge time of less than about 0.2 millisecond.

11. A method of producing repetitive energy pulses comprising the steps of selecting a conducting liquid having a resistivity of less than 25 ohms-cm, establishing a pair of spaced-apart electrodes, passing a physically continuous stream of said conducting liquid from one of said electrodes to the other of said electrodes and repetitively discharging an energy storage means between said electrodes and through said conducting liquid to repetitively explode said conducting liquid.

12. The method of claim 11 further characterized in that the spacing between said electrodes is established at a distance greater than the breakdown potential distance of the gaseous environment of said electrodes at the conditions prevailing just prior to the time that the conducting liquid is exploded.

13. The method of claim 11 further characterized by the step of measuring the resistance of the stream of conducting liquid and comparing it to the resistance of a column of said conducting liquid having the same cross section and length to insure that the stream of conducting liquid is a physically continuous stream.

14. The method of claim 11 further characterized in that the conducting liquid has a resistivity between about 5 microohms-cm and 10 ohms-cm.

15. The method of claim 11 where the conducting liquid is selected from the group consisting of mercury, potassium, sodium, rubidium with caesium, indium, silver, tin, zinc with gallium, indium with mercury, so-

dium with mercury, rubidium with mercury, thallium with mercury, potassium with sodium, rubidium with sodium, caesium, gallium, gold with sodium, bismuth with indium, cadmium with sodium, mercury with potassium, potassium with rubidium, lithium, sodium chloride solution, calcium chloride solution, sodium sulfate solution, potassium iodide solution, nickelous acetate solution, tetramethyl ammonium bromide solution and silver nitrate solution.

16. The method of claim 11 where the conducting liquid is mercury.

17. Apparatus for repetitively producing high energy radiation comprising a pair of spaced-apart electrodes, reservoir means for holding a flowable conducting material, orifice means in electrical contact with one of said pair of spaced-apart electrodes and communicating with said reservoir for jetting a fine stream of said material to the other of said pair of electrodes, discharge box means formed about said electrodes said discharge box means formed of a nonconducting material and energy storage means operably connected to said electrodes, said energy storage means having a capacity sufficient to cause said stream to explode to produce a light flash of high ultraviolet output.

18. Apparatus for repetitively producing light flashes comprising a pair of spaced-apart electrodes, reservoir means for holding a conducting liquid, orifice means in electrical contact with one of said electrodes, said orifice means receiving said liquid from said reservoir and directing a fine stream of said liquid to the other of said electrodes and energy storage means capable of supplying a potential of at least one kilovolt and having a discharge time of less than about 0.2 millisecond to explode said stream operably connected to said electrodes.

19. A method of producing repetitive light flashes comprising establishing a jet stream of a flowable conducting liquid having a resistivity of less than 25 ohmcm between two spaced-apart electrodes and repetitively subjecting said stream to a potential to cause said stream to explode to produce repetitive flashes of high ultraviolet output.

* III t 

1. Apparatus for repetitively producing high energy pulses comprising a pair of spaced-apart electrodes, reservoir means for holding a liquid-conducting substance, a liquid conducting substance having a resistivity of less than 25 ohms-cm in said reservoir, orifice means in electrical contact with one of said pair of spaced-apart electrodes and communicating with said reservoir foR jetting a physically continuous stream of said liquid conducting substance to the other of said pair of electrodes and energy storage means operably connected to said electrodes, said energy-storing means having a capacity sufficient to cause said stream to explode.
 2. The apparatus of claim 1 where the liquid-conducting substance has a resistivity of between 5 microohms-cm and 10 ohms-cm.
 3. The apparatus of claim 1 further characterized by discharge box means formed about said electrodes, said discharge box means being formed of a nonconductive material.
 4. Apparatus for repetitively producing high energy pulses comprising a pair of spaced-apart electrodes, the said electrodes being spaced apart at least a predetermined minimum distance depending on the gaseous environment of the electrodes to prevent breakdown of the gas when a predetermined potential is applied across said electrodes, reservoir means for holding a conducting liquid, a conducting liquid in said reservoir means, said conducting liquid having a resistivity of less than 25 ohms-cm, orifice means in electrical contact with one of said pair of spaced-apart electrodes and communicating with said reservoir for jetting a physically continuous stream of said conducting liquid to the other pair of said electrodes, said stream conducting liquid having a relatively small cross section and having substantially the same resistance as a column of similar conducting liquid of the same length and cross section and energy storage means operably connected to said electrodes, said energy storage means having a capacity sufficient to cause said stream to explode.
 5. Apparatus as in claim 4 where the conducting liquid is selected from the group consisting of mercury, potassium, sodium, rubidium with caesium, indium, silver, tin, zinc with gallium, indium with mercury, sodium with mercury, rubidium with mercury, thallium with mercury, potassium with sodium, rubidium with sodium, caesium, gallium, gold with sodium, bismuth with indium, cadmium with sodium, mercury with potassium, potassium with rubidium, lithium, sodium chloride solution, calcium chloride solution, sodium sulfate solution, potassium iodide solution, nickelous acetate solution, tetramethyl ammonium bromide solution and silver nitrate solution.
 6. Apparatus of claim 4 where the conducting liquid has a resistivity of between 5 microohms-cm and 10 ohms-cm.
 7. Apparatus of claim 4 characterized in that the energy storage means includes a capacitor.
 8. Apparatus of claim 4 characterized in that the energy storage means includes a coil.
 9. Apparatus of claim 4 characterized in that the energy storage means is capable of supplying a potential of at least 1 kilovolt.
 10. Apparatus of claim 4 characterized in that the energy storage means is capable of supplying a potential of at least 1 kilovolt and has a discharge time of less than about 0.2 millisecond.
 11. A method of producing repetitive energy pulses comprising the steps of selecting a conducting liquid having a resistivity of less than 25 ohms-cm, establishing a pair of spaced-apart electrodes, passing a physically continuous stream of said conducting liquid from one of said electrodes to the other of said electrodes and repetitively discharging an energy storage means between said electrodes and through said conducting liquid to repetitively explode said conducting liquid.
 12. The method of claim 11 further characterized in that the spacing between said electrodes is established at a distance greater than the breakdown potential distance of the gaseous environment of said electrodes at the conditions prevailing just prior to the time that the conducting liquid is exploded.
 13. The method of claim 11 further characterized by the step of measuring the resistance of the stream of conducting liquid and comparing it to the resistance of a column of said conducting liquid having the same cross section and length to insure that the streaM of conducting liquid is a physically continuous stream.
 14. The method of claim 11 further characterized in that the conducting liquid has a resistivity between about 5 microohms-cm and 10 ohms-cm.
 15. The method of claim 11 where the conducting liquid is selected from the group consisting of mercury, potassium, sodium, rubidium with caesium, indium, silver, tin, zinc with gallium, indium with mercury, sodium with mercury, rubidium with mercury, thallium with mercury, potassium with sodium, rubidium with sodium, caesium, gallium, gold with sodium, bismuth with indium, cadmium with sodium, mercury with potassium, potassium with rubidium, lithium, sodium chloride solution, calcium chloride solution, sodium sulfate solution, potassium iodide solution, nickelous acetate solution, tetramethyl ammonium bromide solution and silver nitrate solution.
 16. The method of claim 11 where the conducting liquid is mercury.
 17. Apparatus for repetitively producing high energy radiation comprising a pair of spaced-apart electrodes, reservoir means for holding a flowable conducting material, orifice means in electrical contact with one of said pair of spaced-apart electrodes and communicating with said reservoir for jetting a fine stream of said material to the other of said pair of electrodes, discharge box means formed about said electrodes said discharge box means formed of a nonconducting material and energy storage means operably connected to said electrodes, said energy storage means having a capacity sufficient to cause said stream to explode to produce a light flash of high ultraviolet output.
 18. Apparatus for repetitively producing light flashes comprising a pair of spaced-apart electrodes, reservoir means for holding a conducting liquid, orifice means in electrical contact with one of said electrodes, said orifice means receiving said liquid from said reservoir and directing a fine stream of said liquid to the other of said electrodes and energy storage means capable of supplying a potential of at least one kilovolt and having a discharge time of less than about 0.2 millisecond to explode said stream operably connected to said electrodes.
 19. A method of producing repetitive light flashes comprising establishing a jet stream of a flowable conducting liquid having a resistivity of less than 25 ohm-cm between two spaced-apart electrodes and repetitively subjecting said stream to a potential to cause said stream to explode to produce repetitive flashes of high ultraviolet output. 